1. Field of the Invention
The present invention relates generally to a high efficiency brushless direct current motor or generator and more specifically to an improved modular electric machine utilizing a modular stator construction, and modular rotor magnetic elements to produce an inexpensive, high power density motor. The invention further comprises a method of operation of an electric machine that results in a motor or generator capable of exceptional power density.
2. Description of the Related Art
Many designs and configurations of electric motors and generators are presently in use in the field of alternating current (AC) and direct current (DC) motors. Both AC and DC motors are in widespread use in many industries and are increasingly utilized in transportation applications where high-torque and low power consumption are two seemingly contradictory goals. The magnetic motor industry is continuously attempting to design motors with increased and enhanced efficiency to facilitate motor operation with a minimum of electric power consumption, thereby gaining competitive advantage. Motors utilizing an array of differing rotor and stator designs have been devised in an attempt to provide higher power densities throughout the motor rotor and stator, thereby leading to enhanced operational efficiency.
However, there is a need in the art for a motor or generator assembly employing a more efficient rotor and stator design to enhance electromagnetic flux density in the motor, particularly at the pole placements between rotor and stator elements. Traditionally, many motors utilize a single array of north-south-north magnets secured to a steel hub via an epoxy resin to form a magnetic rotor and/or stator. These prior art designs produce rotors that have one magnet pole per rotor or stator tooth that interacts electromagnetically with the complementary rotor or stator.
However, a design that permits multiple points of electromagnetic interaction between points on the rotor and stator of the motor would lead to enhanced efficiency and is therefore highly desirable. Furthermore, a motor design taking advantage of the superior magnetic properties of an efficient permanent magnet circuit to increase power density is also desirable.
Additionally, most prior art motors employ stator tooth windings that necessarily require additional machine weight, field losses, and axial length due to the arrangement of the end windings. Thus there is a need in the art for a motor that reduces the electromagnetic disadvantages as well as the manufacturing disadvantages of conventional DC motor designs.
Finally, many prior art electric machines that operate at relatively high electromagnetic flux densities suffer from overheating. The high field strength present at the rotor or stator hubs produces eddy currents and other undesirable electromagnetic interactions with surrounding components which in turn produces a great deal of heat. Thus there is a need for a lightweight rotor or stator hub in conjunction with a high-power density motor that rapidly and efficiently dissipates the excess heat generated by a high power density electric machine.